Scientists seeking the missing link between modern Europeans and Neanderthals ought to head back to Africa, according to a new study that could prune some of the younger branches of the evolutionary tree. Researchers took another look at a common fossil used to date early humans - teeth. By looking at the pattern of points on molars of European fossils, older African and Asian fossils, and modern humans, they arrived at a picture of what the teeth of a common ancestor might have looked like.

Scientists have discovered the fossilized brain of an animal that lived 520 million years ago. It is the oldest mostly intact nervous system to have ever been found. The incredible ancient brain and nervous system, described in the journal Nature, belongs to an Alacomenaeus , a member of the mega-claw family. These animals earned the name "mega-claw" ( megacheiran ), because they have two large scissor-like appendages that protrude from the top of their heads. Megacheirans lived in the early Cambrian-era ocean, swimming and scuttling around with nearly one dozen little legs, or swimmerettes.

Scientists have discovered the last blood meal of a 46 million-year-old female mosquito, and isolated a little fragment of the protein in it, too. The findings, published this week in the journal Proceedings of the National Academy of Sciences, show that even if DNA can't survive tens of millions of years - sorry, "Jurassic Park" fans - other biomolecules might. Even though there are around 14,000 species of blood-feeding insects in existence...

After consulting for several years with Los Angeles County Museum of Art Director Michael Govan over what might replace four older structures on the museum's campus, the acclaimed Swiss architect Peter Zumthor has fashioned a model of a distinctive new building of undulating walls that, seen from above, looks like a splatter of tar - an homage to the La Brea Tar Pits next door on Wilshire Boulevard. Using the tar pits as inspiration is a great idea. But encroaching on them is a problem.

Re "For students, fossil fuels become an issue of conscience," Aug. 26 Congratulations to the students of San Francisco State University who persuaded the trustees of their college to divest from fossil fuel companies. However, this article has an egregious omission: the carbon bubble. This bubble will likely pop and fossil fuel stocks will crash in the next decade or so if we are to preserve the planet for future generations. According to the climate change activist group 350.org, the planet cannot handle more than 565 gigatons of carbon emissions before 2050.

In the 1980s, student protests against apartheid led universities to sell off stocks in companies doing business in South Africa. More recently, concerns about genocide in Darfur, the health effects of tobacco and handgun violence led to more college divestments. Now another issue - the effect of fossil fuels on global temperatures - is rousing a new generation of student activists to press their schools to drop coal, petroleum and natural gas investments from campus endowments. Student campaigns, such as "Fossil Free UC," are underway at about 300 colleges and universities nationwide, organizers estimate.

Mammals first appeared 215 million years ago during the Triassic period, according to a new study in the journal Nature. Wait, no, they first showed up 175 million years ago during the Jurassic period, said another study in the same issue of the journal. Who's right? The answer may rest in the middle of your ear. A bit of background: The origin of our mammalian ancestors has long been shrouded by an incomplete fossil record. The first breakthrough occurred during World War II, when German paleontologist Walter Georg Kühne was imprisoned in Britain and filled his hours by examining fossils.

The Tyrannosaurus rex of "Jurassic Park" fame chases any prey that moves, then devours it with a bone-crushing gnash of its enormous jaws and serrated teeth. But paleontologists don't necessarily back Steven Spielberg's portrayal of T. rex , with some saying it may have simply scavenged the remains of dead animals it happened to find. Now scientists have unearthed what they say is the first direct evidence that the dinosaur king hunted its prey, further supporting its reign at the top of the Cretaceous food chain.

Somewhere between 390 to 360 million years ago, a four-legged vertebrate, or tetrapod, crawled out of the water and gave rise to the amphibians, reptiles and mammals we see today. Scientists have established that this creature descended from fish and evolved its limbs and digits underwater, before its transition to dry ground. Life on land was accompanied by major modifications of the vertebrate skeleton, such as the evolution of a neck. Sandy Kawano, a graduate student at Clemson University, wondered how that transition from surf to turf might have happened - and she turned to modern animals to figure it out. Fossils of such science fiction muses as Ichthyostega , an early tetrapod, provide information on these organisms' appearance, but you can't get behavior out of old bones, Kawano said.

In December 2008, University of Utah economics student Tim DeChristopher impulsively - and successfully - bid on 12 parcels of land in southern Utah whose oil and drilling rights were being auctioned off by the Bureau of Land Management under outgoing President George W. Bush. That might have been OK had DeChristopher planned to pay for and exploit the properties. But the 27-year-old preservationist was actually at the sale as part of a peaceful protest against the fossil fuel industry when he was randomly handed a bidder's paddle: No. 70. DeChristopher's staunch and inspiring journey after that fateful auction (which was later invalidated by incoming Interior Secretary Ken Salazar)